Embankments or berms are widely used in civil, industrial, and municipal applications for reservoirs for the retention and storage of liquids. As used in this disclosure, embankments, levees, retention dikes, dams and berms will collectively be referred to as berms. The liquids stored by these berms can range from storm water to hazardous materials such as fracing water or industrial process by-products. Industrial reservoirs are typically land-locked within existing facilities with little or no room to expand the reservoir in a horizontal direction due to adjacent structures, property owners, buried utilizes, etc. The need for additional reservoir volume capacity may occur for multiple reasons, including but not limited to expansions in process or treatment requirements. For the reasons described above, facility owners are faced with limited options to increase reservoir capacity.
One application of industrial reservoirs is the surface storage of brine solution at salt dome storage facilities. These facilities store hydrocarbon products in underground caverns that have been formed by dissolving salt deposits from naturally occurring salt dome formations. The brine solution is pumped underground to displace the hydrocarbon products out of the storage and into the facility for distribution to downstream facilities. When new product is pumped into the cavern, the brine is displaced through pipe systems to the surface storage reservoirs.
In the State of Texas, for example, regulations require an operating freeboard of 2 to 3 feet between the maximum operating fluid elevation and the top of the berm. Because this freeboard is by nature at the top of the berm and at the widest part of the levee (due to the sloping berm walls as described below), the storage lost to the freeboard requirement can be over 13% of the total available capacity of the reservoir. These reservoir are typically installed to utilize the maximum available footprint and cannot be easily expanded. Land restrictions make it difficult or impossible to add additional reservoirs. It is also expensive to remove and build a new berm wall constructed of soil.
Berms are also common in stationary flood control structures such as levees and dams. There are an estimated 100,000 miles of levees in the United States alone. It is sometimes necessary to raise the effective fluid retention height of these levees due to increases in upstream development that lead to increased runoff and therefore increased flood elevations. This is traditionally done by adding soil to the levee, constructing concrete barrier walls, or adding a gravity fill structure to the crest of the levee. These gravity fill systems rely on the weight of the added structure to resist the fluid pressures from the contained fluid.